<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>土豆案例</title>
  <style>
    .tudou {
      position: relative;
      width: 444px;
      height: 320px;
      background-color: #ccc;
      margin: 30px auto;
    }

    .tudou img {
      width: 100%;
      height: 100%;
    }

    .mask {
      display: none;
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(0, 0, 0, .4) url(images/arr.png) no-repeat center;
    }

    .tudou:hover .mask {
      display: block;
    }
  </style>
</head>

<body>
  <div class="tudou">
    <div class="mask"></div>
    <img src="./images/tudou.jpg" alt="视频图片">
  </div>
</body>

</html>